As can be appreciated, the arrangement of a given quantity of sawn lumber into stacks can facilitate handling, transportation, storage and/or various processing, such as drying and the like, of the lumber. Various types of lumber stackers are known to those of ordinary skill in the art, which can be employed for automatically forming bulk lumber into stacks of a predetermined size. In general, such lumber stackers are configured to stack lumber by forming, and then stacking, one complete layer or course at a time.
One category of lumber stackers is generally known as “stickering stackers” to those skilled in the art. Stickering stackers are configured to automatically place “stickers” or “sticks” between adjacent courses of lumber as part of the stacking process. The placement of sticks between courses of lumber in the stack can serve several purposes. For example, placement of the sticks in a direction transverse to the direction of the lumber can help tie the stack together. As another example, placement of the sticks between courses can create spaces between the lumber, which can facilitate drying or other treatment processes.
Within the category of stickering stackers is a subcategory known to those in the art as “underlayment stickering stackers.” An underlayment stickering stacker is defined as a stickering stacker that is configured to form a given lumber course with underlaid sticks, and then to place the given course along with the underlaid sticks onto the stack. That is, an underlayment stickering stacker is configured to form a given lumber course on top of the associated sticks, and to move the lumber course together with the associated underlaid sticks so as to place the course and sticks onto the stack.
Conventional underlayment stickering stackers often include several main subassemblies or devices. Such devices can include, for example, one or more of an infeed conveyor, a carriage/fork device, a rake-off device, a stick device, and a hoist device. Conventional underlayment stickering stackers can also include associated actuators, mechanisms, and controls corresponding to each of the devices.
During operation of conventional underlayment stickering stackers, the infeed conveyor can facilitate formation of a course of lumber at a course-forming station. The stick device is operated to facilitate insertion of sticks beneath the lumber course as the lumber course is being formed. The carriage/fork device is then operated to pick up the lumber course along with the underlaid sticks from the course-forming station, and to move the course and sticks to a stacking station above the hoist device.
The carriage/fork device, in conjunction with the rake-off device, then places the lumber course and associated underlaid sticks onto a previously placed lumber course to form the stack (alternatively, the course is placed directly onto the hoist, if the course if the first course of a stack). More specifically, the rake-off device can be lowered after the carriage/fork is moved into position above the hoist device. Then, as the carriage/fork device is withdrawn from the stack, the rake-off device contacts the lumber course and associated underlaid sticks to allow the carriage/fork device to be pulled from beneath the lumber course and sticks. In this manner the lumber course and associated underlaid sticks are deposited on the stack. The hoist device can then be moved downward after each course is placed on the top of the stack in order to keep the top of the stack at a substantially constant elevation.
It is generally understood by those of ordinary skill in the art that each of the main devices of a conventional underlayment stickering stacker, as described above, can include or be made up of a plurality of subcomponents. For example, the infeed conveyor can include a board unscrambler, an even ending rollcase, and feed chain. Similarly, the carriage/fork device can include a carriage configured to move in a substantially horizontal direction between the course forming station and the stack, as well as a fork supported by the carriage, wherein the fork can be configured to pivot and/or move in a substantially vertical direction.
Likewise, the stick device can include one or more of a singulating feed mechanism, a stick distribution mechanism, and a stick inserter mechanism. The singulating feed mechanism can be configured to singulate bulk sticks and to selectively place individual sticks onto the stick distribution system. The stick distribution system can be configured to selectively deliver sticks to predetermined positions below the carriage/fork device. The stick inserter mechanism can be configured accept the sticks from the stick distribution system and to facilitate insertion of the sticks between the fork and the course being formed at the course forming station. It is further understood that each of these subcomponents can include associated drive linkages, actuators and control components.
Conventional underlayment stickering stackers include one or more types of actuation devices to impart motion and power to the major moving parts in conjunction with associated drive linkages and the like. For example, conventional stackers often employ hydraulic cylinders and/or hydraulic motors and/or conventional electric motors, along with various linkages, power transmission systems, and other such mechanisms, to impart motion and power to the major moving parts of the stacker.
Control systems of conventional underlayment stickering stackers often include one or more processors and/or controllers as well as a variety of other peripheral control devices such as limit switches, proximity switches, automatic valves, relays and the like. The processors and/or controllers that are employed to operate conventional underlayment stickering stackers generally include a set of computer-executable instructions or code (e.g., a “program”) that, together with other components, is configured to control operation of the actuation devices to thereby enable substantially automatic operation of the stacker.
Those skilled in the art will understand that conventional stackers can include other components and the like which are not specifically discussed herein, but which are known to those of ordinary skill in the art.